Harmonic Reject Receiver Architecture and Mixer

1. A quadrature mixer comprising: one or more harmonic reject mixers, each of the one or more harmonic reject mixers comprising: a common RF input, a control input coupled to a control signal, an LO generator operable to generate a plurality of phased LO signals, wherein each of the plurality of phased LO signals is generated according to a respective transition of a plurality of transitions of the control signal, and a plurality of switching mixer circuits, wherein each of the plurality of switching mixer circuits comprises a first input coupled to the common RF input and a second input coupled to one of the plurality of phased LO signals; a control generator operable to generate the control signal comprising the plurality of transitions during a period of each phased LO signal; a first combiner having inputs coupled to a first subset of outputs from the one or more harmonic reject mixers, and an output configured to provide a quadrature output; and a second combiner having inputs coupled to a second subset of outputs from the one or more harmonic reject mixers, and an output configured to provide an in-phase output; wherein the first subset of outputs is shifted with respect to the second set of outputs.

2. The quadrature mixer of claim 1 , wherein the control signal controls the transitions of each switching mixer circuit and each switching mixer circuit transitions once in each LO period.

3. The quadrature mixer of claim 1 , wherein the in-phase output is an in-phase intermediate frequency (IF) output and the quadrature output is a quadrature intermediate frequency (IF) output.

4. The quadrature mixer of claim 2 , wherein the first combiner applies one or more weights to the first subset of outputs and the second combiner applies one or more weights to the second subset of outputs.

5. The quadrature mixer of claim 4 , wherein the weight is based on a sinusoidal function of the phase associated with the corresponding switching mixer.

6. A method of quadrature mixing, the method comprising: generating a single control signal comprising a plurality of transitions; generating a plurality of distinct phased LO signals, wherein the plurality of transitions of the single control signal occur during a period of each distinct phased LO signal, and wherein each of the plurality of distinct phased LO signals is generated according to a respective transition of the plurality of transitions of the single control signal; mixing an input signal with each of the plurality of distinct phased LO signals to generate a plurality of mixer outputs; combining a first subset of mixer outputs to generate a quadrature mixer output; and combining a second subset of mixer outputs to generate an in-phase mixer output; wherein the first subset of mixer outputs is shifted with respect to the second set of outputs.

7. The method of quadrature mixing of claim 6 , wherein the in-phase mixer output is an in-phase intermediate frequency (IF) output and the quadrature mixer output is a quadrature intermediate frequency (IF) output.

8. A quadrature mixer comprising: an oscillator operable to generate a control signal comprising a plurality of transitions; an LO generator operable to generate a plurality of distinct phased local oscillation (LO) signals, wherein the plurality of transitions of the control signal occur during a period of each distinct phased LO signal, and wherein each of the plurality of distinct phased LO signals is generated based on a respective transition of the plurality of transitions of the control signal; a plurality of mixers, each mixer in the plurality of mixers being operable to receive a common radio frequency (RF) signal and being driven by one of the plurality of distinct phased LO signals; a plurality of gain stages operable to provide a plurality of weighted mixer outputs, each gain stage in the a plurality of gain stages being operable to apply a particular weight to an output of a particular mixer in the plurality of mixers; a first combiner operable to combine a first subset of weighted mixer outputs and provide a quadrature output; and a second combiner operable to combine a second subset of weighted mixer outputs and provide an in-phase output.

9. The quadrature mixer of claim 8 , wherein the particular weight applied to the output of the particular mixer is based on a sinusoidal function of the phase corresponding to the distinct transition that drives the particular mixer.

10. The quadrature mixer of claim 8 , wherein each of the plurality of mixers comprises a switching mixer.

11. The quadrature mixer of claim 8 , wherein each of the plurality of mixers comprises a CMOS switching mixer.

12. The quadrature mixer of claim 8 , wherein the common RF signal comprises a specified channel and a difference between a frequency of the specified channel and a frequency of the LO signal is less than a bandwidth of the specified channel.

13. The quadrature mixer of claim 12 , wherein the in-phase output is baseband and the quadrature output is baseband.

14. The quadrature mixer of claim 12 , wherein the in-phase output is substantially baseband and the quadrature output is substantially baseband.

15. The quadrature mixer of claim 14 , wherein the difference between the frequency of the specified channel and the frequency of the LO signal is non-zero.

16. The quadrature mixer of claim 8 , wherein the common RF signal comprises a specified channel and a difference between a frequency of the specified channel and a frequency of the LO signal is greater than a bandwidth of the specified channel.

17. The quadrature mixer of claim 16 , wherein the in-phase output is an in-phase intermediate frequency (IF) output and the quadrature output is a quadrature IF output.

18. The quadrature mixer of claim 8 , wherein signals in the second subset of weighted mixer outputs are shifted relative to signals in the first subset of weighted mixer outputs.

19. The quadrature mixer of claim 8 , wherein the first combiner is a first summing circuit and the second combiner is a second summing circuit.

20. The quadrature mixer of claim 8 , wherein there is an odd number of mixers in the plurality of mixers.

21. The quadrature mixer of claim 8 , wherein a number of distinct transitions in the plurality of transitions is equal to a number of mixers in the plurality of mixers.

22. The quadrature mixer of claim 8 , wherein a number of mixers in the plurality of mixers is equal to a number of weighted mixer outputs in the first subset of weighted mixer outputs.